Doug's Mountain Journal
A Chronicle of Natural History on San Bruno Mountain

Doug Allshouse has been writing his seasonal Mountain Journal for many years. We are very pleased to share his reflections on the natural history of the Mountain. Together with David Nelson, he wrote San Bruno Mountain: A Guide to the Flora and Fauna. The book was published by Heyday Books in November 2022 and can be purchased here.

Spring 2023

I’ve noticed that lately things have been pretty quiet, but that changed on a mid-June morning. So who was talking to me? How about a Wilson’s warbler, Orange-crowned Warbler, Song Sparrow, Flicker, Raven, Purple Finch, and Black-headed Grosbeak! Not all at once thank goodness. It is nesting season, which means that the quiet birds are busy feeding the kids and the noisy ones are still trying to hook up; best of luck boys.

Has anyone noticed that we are closing out a rather robust rainy season? Today, June 30, is the last day of the 2022-2023 rain season. This has been the wettest season in six years, 37.10 inches, beating 2016-17’s 36.22 by 0.88 inches! The big difference this season was 33.36 inches of rain between December 1 and March 31 that led to major mudslides and damage in Buckeye and Owl Canyons. I had heard that Firth Canyon had some trouble and some major damage in Brisbane Acres, but Buckeye and Owl were monumental once-in-a-century-or-more event. Stay tuned for detailed reports of both canyons. Considering all the rain, the flowering shrubs and forbs were rather late this season and there was a very good reason for that—cold temperatures! I don’t keep records of temperatures, but all winter and into spring the temperatures were definitely 10-25 degrees cooler than normal.

I have been working on the removal of nasty narrow-leaf clover on the Ridge Trail that started in 2019. The Latin name Trifolium angustifolium literally means “three-leaf, and narrow-leaf”. It happens to be near the first reintroduction site of the bay checkerspot butterfly. By forming invasive monocultures it also adds nitrogen to the soil, and encourages other weeds to move in. Despite a four-year effort removing over 5,000 plants the clover is not giving up easily. Sweet fennel is also beginning to make its presence known. The area is rather rich in silver lupine which is a prime larval host plant for the mission blue larvae, and is also packed with native purple owl’s clover (Castilleja exserta subsp. latifolia), which is such a pretty plant.

Twinberry (Lonicera involucrata var. ledebourii) also qualifies for that category. Named after Johann Lonitzer and C. F. Ledebour, it is a perennial shrub that grows three to ten feet tall and prefers some moisture. The twin tubular flowers are yellow, tinged with orange or red and are subtended by showy red bracts. The magic happens after pollination. The twin tubes shrivel and die and are replaced by two shiny, black berries ensconced in brilliant red bracts that have grown larger. The contrast of black berries and red bracts is a striking example of natural beauty. There are several bushes on the upper Bog Trail that really produce a nice show in May and June.

I read an article in the San Francisco Chronicle recently about the plethora of poison hemlock (Conium maculatum) that appeared after the heavy rains we received. I have noticed that another weed, ox-eye daisy (Leucanthemum vulgare), has also exploded this spring with huge displays appearing along trails. This is the typical daisy found in flower shops. Ironically, a winter-spring weed known by several common names—yellow oxalis, Bermuda buttercup, sour grass (Oxalis pes-caprae)—has not been as prevalent as it usually is when heavy rains occur. It seems like there was more last year. Was it too much of a good thing or cold weather?

In the Winter 2023 Journal I showed some photos of mudslide damage Owl and Buckeye Canyons. In mid-April I took a grueling hike up the west side creek from the base of Owl to the top with a friend to survey the landscape. It was tough sledding and something I’ll never do again. It took us almost four hours to complete, but a wonderful discovery was waiting for us. After we crawled out of subsidence that caused the major mudslide, I saw a nice patch of delicate wildflowers. I should tell you that the upper grasslands were packed with gold fields, lupines, and poppies that I had seen during February and March. This patch and a couple more were located much further down the steep grassy slopes in upper Owl than I had walked a couple of months before—probably the reason why no one has reported this wildflower since 1990. There were several scattered patches of small-flowered plectritis (Plectritis congesta var. brachystemon), baby blue eyes (Nemophila menziesii var. menziesii), and what turned out to be cream cups (Platystemon californicus).

Originally I thought it was narrow-leaf poppy (Hesperomecon linearis) which had last been reported on San Bruno Mountain in 1903! I was much too tired in April to investigate the entire plant. The plant descriptions for both species on Jepson were nearly identical but the line drawings did differentiate the two by the leaves. Two weeks later David Nelson and I hiked the Ridge Trail and dropped down the ridge to document the plant and get more photos. As soon as we dug up one plant, I could see that the leaves and their position on the stems revealed it to be cream cups, a rare local plant in the poppy family—and a new one for me. It would have been so exciting to record a new observation on Calflora 130 years later, so instead I happily recorded the first one for San Bruno Mountain. The others were in the Edgewood-Crystal Springs-Woodside areas.

I have a deep affinity for the Colma Canyon Dunes, formerly the Daly City Dunes. The whole system warrants a name change since the Colma Formation and the dunes once covered a large portion of Colma, Daly City, San Francisco and the Presidio until the end of World War ll. It resembled a virtual desert of sand occupied by sand-adapted plant species, broken only by creeks flowing to the ocean from the west-facing ravines of the Mission Hills. Now the only remnants in San Mateo County exist at the western end of Colma Canyon from the old Colma dump site to the dunes above Bonnie Street. To a lesser degree, but nevertheless still an active vein of sandy soil, there exist remnants along the western edges of the Bog and the Saddle Trails dating back 125,000 to 80,000 years ago during the last interglacial period when all the glaciers melted and San Bruno Mountain and the hilly areas along the bay were islands.

The dunes are home to several rare and endangered dune plant species (lessingia and San Francisco spineflower) that are now found only on the dunes and the Presidio. There are four species of dune suncups or evening primroses that are very rare and one is a southern California species whose closest relative is in San Luis Obispo County. These plants rely on the erosion of sand by the wind to create open space for germination of the seeds, and the very fine hydrophilic sand allows water to penetrate immediately rather than pooling which is common to hydrophobic sand on beaches. I am worried that European annual grasses, ice plant, and invasive crown daisy threaten the balance of nature on the dunes. Even the places where restoration has been done are beginning to show signs of losing the battle in this unique ecosystem. The lee side of the dune is covered in grasses and shrubs due to the absence of wind erosion.

There is a tiny window each year when these six species coexist. Join me next June for a hike on the dunes to see this rather unique piece of geology and plants. In the meantime, get out and about.

See you on the Mountain…